Sensitivity of MRSA isolated in our hospital to various antibacterial agents: changes over 5 years]

Among methicillin resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens during 5 years period from 1998 through 2002 in Cancer Institute Hospital, Japanese Foundation for Cancer Research, a total of 100 strains, one per patient, were successively selected each year, and their sensitivity to various antibacterial agents was measured to assess changes over five years in their sensitivity to these drugs. The following results were obtained. 1. Little or no change was observed in the sensitivity to arbekacin during 5 years period. In contrast, a tendency toward decreased sensitivity was observed with vancomycin and teicoplanin, with the tendency more marked with the latter agent. 2. Arbekacin, vancomycin and teicoplanin inhibited the growth of all clinical isolates in the year 2002 at 3.13, 1.56 and 12.5 microg/mL, respectively. 3. The sensitivity to netilmicin tended to decrease over the years. 4. Minocycline, imipenem and ofloxacin had little or no antibacterial activity, with MIC50 of more than 12.5 microg/mL throughout the years studied. 5. Ninety five percent of MRSA strains isolated during the five years were classified as coagulase type II, and enterotoxins were found to be type C in 51% and type AC in 17% of the strains studied.